Rubio: Donald Trump won't be Republican nominee

ORFORD, N.H. (AP) — Florida Sen. Marco Rubio says Donald Trump will not be the Republican presidential nominee because his message is not an optimistic one.

Rubio has largely shied away from taking on Trump, the billionaire businessman sitting atop polls of the Republican rivals.

In recent weeks, candidates such as Kentucky Sen. Rand Paul and former Florida Gov. Jeb Bush have started to go head-to-head with Trump. Rubio's criticisms Wednesday were measured, even when asked about Trump's comment that Rubio is "disloyal" and "disrespectful" for running against Bush, who was Rubio's mentor in Florida politics.

"I think our nominee is going to be someone that embraces the future, that understands the opportunities before us, that's optimistic but realistic about the challenges before us," Rubio told reporters after a meet-and-greet event in New Hampshire's North Country.

Speaking to a small crowd outside an auto body shop in a town of roughly 1,200, Rubio focused largely on his message of ushering in a new era of prosperity. He also drew a contrast between his message and Trump's, which centers on the slogan Make America Great Again.

"I understand what he's trying to say," Rubio said, "but I would remind him that America is great, and you know why I know America is great? Because ask yourself this question: Who would you trade places with?"

Rubio said: "The issue's not that America isn't great, the issue is that America has the chance to be greater."

Trump's rhetoric on immigration in particular has some Republicans worried about the party's ability to attract support from Hispanic voters, pivotal in the general election. Rubio didn't answer when asked whether Trump's comments are hurting that effort.

"Ultimately the Republican Party will reach out to all voters based on who our nominee is, and I don't believe Donald Trump will be our nominee," he said.